Construction and validation of augmented reality navigation system based on visual tracking guide template in spinal surgery

Objective To construct an augmented reality (AR) navigation system model based on visual tracking guide template during pedicle screw placement, and to evaluate the application value of the model. Methods A visual tracking guide template was designed and fabricated for spinal surgery navigation. The visual tracking guide template and AR equipment were used to complete image registration and real⁃time tracking between AR images and real objects. With the assistance of AR navigation technology, 2 operators performed screw insertion with Kirschner wire respectively. According to the distance between the insertion point of Kirschner wire and the visual tracking guide template, the model was divided into adjacent group (< 100 mm) and distant group (100-200 mm). The accuracy of the AR navigation system was evaluated by comparing and analyzing the insertion point error value and angle error value of different operators and the adjacent group and the distant group. Results The 2 operators successfully completed the screw placement, and a total of 100 cases of insertion point error value and angle error values were obtained. There was no significant difference in the insertion point error (t = 0.835, P = 0.406) and angle error value (t = 0.220, P = 0.826) between the 2 operators. The error value of the insertion point in the distant group was higher than that in the adjacent group (t = 3.221, P = 0.002), while there was no significant difference in the angle error value between the 2 groups (t = 1.786, P = 0.077). Further, the insertion point error value is decomposed into x vaue and y value. There were significant differences in x value (t = 4.980, P = 0.000) and y value (t = 2.416, P = 0.018) between the adjacent group and the distant group. Conclusions The AR navigation system model based on visual tracking guide template is preliminarily constructed, and the navigation accuracy is evaluated. As the distance between the insertion point and the visual tracking guide template increases, the positioning ability of the insertion point decreases, but the angle directivity is stable.